1. Field of the Invention
The present invention relates to a two-dimensional spectral characteristic measuring apparatus for measuring the two-dimensional spectral characteristics of a sample.
2. Description of the Related Art
In order to measure the two-dimensional, or planar spectral characteristics of a sample, the following methods (1) through (3) have conventionally been used.
(1) A turntable having a plurality of band-pass filters of which the passbands are different from one another is arranged between a sample and an imaging means for imaging a two-dimensional image of the sample, and this turntable is turned to sequentially change the filters through which light from the sample penetrates.
(2) There is provided a plurality of sets having filters of which the passbands are different from one another, each set being comprised of a band-pass filter of a very small size and an imaging means, and they are made to scan a sample.
(3) A plurality of dichroic mirrors of which the light reflection wavelengths are different from one another are arranged parallel to each other, and imaging means corresponding to the directions in which lights from a sample are reflected are arranged, whereby the two-dimensional image of the sample is imaged by the imaging means.
However, the above methods (1) and (2), which necessitate the turning of the turntable and a structure for scanning the aforementioned sets, lead to a complicated apparatus. Furthermore, much time is necessary for the turning operation and the scanning operation, and this has led to the problem that the measurement cannot be executed in a short time.
In the case where the turntable is turned to change the filter, the spectral characteristics at different wavelengths cannot be simultaneously measured. In the case where the aforementioned sets are made to scan, the two-dimensional spectral characteristics cannot be simultaneously measured. Therefore, both of the above methods have had the problem that a moving sample cannot be correctly measured.
According to the above method (3), the measurement can be executed in a short time and spectral characteristics at different wavelengths can be simultaneously obtained.
However, the method necessitates a number of processing circuits for processing the data about the received light, outputted from the imaging means by the number corresponding to the number of the imaging means. This has led to the problem that the circuit scale of the processing circuit increases and the apparatus construction becomes complicated.